Hybridization of Atomic Orbitals I
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
Mass Spectrum
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Mass Spectrometry: Branched Alkane Fragmentation
Microbes and Methanogenesis
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Updated: Jul 11, 2026

Protocol for Measuring the Thermal Properties of a Supercooled Synthetic Sand-water-gas-methane Hydrate Sample
Published on: March 21, 2016
Helen Thompson1, Alan K Soper, Piers Buchanan
1ISIS Facility, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX, United Kingdom. h.thompson@rl.ac.uk
This study uses neutron diffraction and computer simulations to track how water structure changes during the formation and breakdown of methane hydrates. The researchers found that the presence of hydrate crystals significantly affects the surrounding water structure. These changes are most noticeable when hydrate crystals are present, and they differ between the formation and decomposition stages. The study suggests that the 'memory effect'—where hydrate forms faster in systems with a prior history—may be due to these structural changes. The results contrast with earlier studies that did not detect such changes when no hydrate crystals were present. The findings provide new insights into the structural basis of the memory effect in hydrate systems.
Area of Science:
Background:
The behavior of water in methane hydrate systems is not fully understood. Prior research has shown that hydrate formation and decomposition involve structural changes in water. However, the exact nature of these changes during different stages remains unclear. No prior work had resolved how water structure evolves in the presence of hydrate crystallites. This gap motivated the current investigation into the water structure during hydrate formation and decomposition. The study aims to address this uncertainty by combining neutron diffraction and empirical modeling. It was already known that hydrate formation can be faster in systems with a prior history of hydrate. The memory effect is a known but poorly explained phenomenon. Understanding the water structure at different stages could clarify the mechanism behind this effect. This paper contributes by tracking structural changes in real time during hydrate formation and decomposition.
Purpose Of The Study:
This study aims to investigate the structural changes in water during methane hydrate formation and decomposition. The focus is on how the presence of hydrate crystallites affects the surrounding water structure. The motivation is to better understand the memory effect in hydrate systems. The researchers propose that the water structure may retain a 'memory' of prior hydrate formation. The study uses neutron diffraction and empirical potential structure refinement to track these changes. The goal is to determine if the water structure differs during formation and decomposition. The researchers also aim to compare results with and without hydrate crystallites present. This approach allows for a detailed analysis of the water structure at different stages of the process.
Main Methods:
Neutron diffraction experiments are conducted using hydrogen/deuterium isotope substitution. These experiments are performed at various stages of hydrate formation and decomposition. Gas consumption is measured simultaneously to track hydrate formation and breakdown. Empirical potential structure refinement simulations are used to analyze the diffraction data. The simulations extract the water structure from the neutron diffraction patterns. The method allows for tracking structural changes in the bulk solution. The approach enables the researchers to compare water structures during formation and decomposition. The combination of experimental and computational methods provides a comprehensive view of the water structure.
Main Results:
The water structure in the remaining liquid changes significantly during hydrate formation and decomposition. These changes are most pronounced when hydrate crystallites are present. The results show that the water structure differs at equivalent stages of formation and decomposition. The methane hydration shell also shows distinct changes during these processes. The presence of hydrate crystallites leads to detectable structural differences. These differences are not observed when no hydrate crystallites are present. The findings suggest that the memory effect is linked to the water structure. The results contrast with earlier studies that did not detect such changes.
Conclusions:
The presence of hydrate crystallites affects the local water structure during formation and decomposition. The water structure differs at equivalent stages of forming and decomposing hydrate. These differences may explain the memory effect in hydrate systems. The results suggest that the water structure retains a history of prior hydrate formation. The findings contrast with previous studies that lacked hydrate crystallites. The study supports the idea that the memory effect is structural in nature. The researchers propose that the water structure influences hydrate formation rates. The conclusions are based on the observed structural differences in the presence of hydrate crystallites.
The water structure in the remaining liquid changes significantly when hydrate crystallites are present.
They use neutron diffraction with hydrogen/deuterium isotope substitution and empirical potential structure refinement simulations.
The presence of hydrate crystallites leads to detectable changes in the water structure that are not observed when they are absent.
The methane hydration shell shows distinct changes during hydrate formation and decomposition stages.
The memory effect is the faster formation of hydrate in systems with a prior history. The study suggests it is linked to water structure changes.
Previous studies did not detect structural changes when hydrate crystallites were absent, but this study shows differences when they are present.